Hawkshadow's '52 M38CDN

Hawkshadow · Post by **Hawkshadow** » Wed May 24, 2017 6:55 pm

Final update to the bellcrank: I used some smaller washers in the top cavity to take up the space and hold the seal in place.

Next I gave up on having a new fuel line made, and ordered a new one from BCA. The differences in quality were immediate compared to the hose out of the fuel line kit from Kaiser. Much thicker brass, proper sized fittings, and better quality hose.

Moving on to repairing the wiring harness to the horn button that was demolished by the fuel that leaked from the cracked fitting. I used an excellent replacement harness also provided by BCA.

Clip wires close to the boot and very gently remove the boot. Then heat and remove the bullets from the switch.

You can see that gasoline absolutely demolishes wire insulation.

Solder in the new harness and re-assemble.

Complete product. To gently put the boot back together, I used a combination of crazy glue and Bondic (UV set plastic compound).

Post by **Ryan_Miller** » Thu May 25, 2017 12:55 pm

looks good!

4x4M38 · Post by **4x4M38** » Thu May 25, 2017 5:25 pm

I figured the fuel line fittings were sub standard, as is the hose material.

Geez there are a lot of people out there buying that stuff blindfolded
without the benefit of communities like ours.

rgmutchler · Post by **rgmutchler** » Fri May 26, 2017 3:04 pm

Jordan,
You mention getting the better fuel lines from BCA, is that a local company? Where are the located or what does BCA stand for.
Thanks
Ralph

4x4M38 · Post by **4x4M38** » Fri May 26, 2017 5:24 pm

Ralph,
BCA is a parts supplier of known quality
in Ontario, Canada, Brian Asbury?

See post below:
http://www.willysmjeeps.com/v2/modules. ... ic&t=10012

I'm quite sure you can get quality hoses not only from
him but Midwest Military, Army Jeep Parts, and Peter DeBella.

It is becoming painfully apparent that if safety and reliability
are at stake one should stay well away from Omix Ada.

Sorry Rommel. As with the sector shaft issue, a defective fuel
hose can be terminal.

Just my two cents.

Jordan has been another lucky guinea pig for
quality testing. Thanks for sharing so we all learn.

Hawkshadow · Post by **Hawkshadow** » Tue May 30, 2017 7:50 pm

I've run in to a problem with one of the back brakes and have run out of things that I can think of to try short of replacing the new brake cylinder.

The system:
Dual master with all new lines, hoses, and cylinders with 1 season of driving. DOT 3.

The problem:
The brake was dragging on the right rear wheel. I removed the drum to inspect and clean and realized that I installed the brake pads backwards so I swapped them around. I made sure that all of the adjustments were at the minimum and when I went to put the drum back on, the brakes were spread too wide for the drum to fit.

I tapped the pads in and used a ratchet strap to pull them together but still no go. I then went around and backed off the push-rod to the master in case it wasn't retracting far enough to allow the pressure to release. No go. As a last ditch I bled some fluid from that cylinder and tried the strap again but no success.

Here are some pictures of where it sits. After using the ratchet strap there is no play left to right when you tap on either pad. Should the cylinder be retracted further?

On this one you can see that I bent the spring slightly trying to get it back on but I don't think that would be causing the problem.

I'm hoping that there is something else to try before writing off the cylinder, but I'm out of ideas.

Thanks in advance.

Post by **wesk** » Tue May 30, 2017 9:48 pm

Have you adjusted your shoe adjusters to the smallest diameter?

Hawkshadow · Post by **Hawkshadow** » Wed May 31, 2017 5:44 am

wesk wrote:Have you adjusted your shoe adjusters to the smallest diameter?

Yes. No tension at all on the uppers and both lowers are at their inner most point.

Post by **wesk** » Wed May 31, 2017 1:32 pm

And you have opened the bleeder fully and allow any pressure to escape?

Have you opened the wheel cylinder and checked for a frozen piston?

Then it is time to measure the drum ID and the shoes OD and compare to specs.

4x4M38 · Post by **4x4M38** » Wed May 31, 2017 2:08 pm

You could pull the other drum and compare how far the pistons are extended.

Post by **wesk** » Wed May 31, 2017 11:24 pm

You can verify this by looking at your brakes or several of the brake photos in the TM's.

Hawkshadow · Post by **Hawkshadow** » Thu Jun 01, 2017 7:30 pm

I compared with the left rear and as expected it wasn't retracted far enough. So I went back and removed the spring on the right. It seemed odd that the pads were at a hard stop but I could compress the cylinder further by fingers and the cylinder could move freely front to back by hand.

So I put the strap around the pads and re-adjusted the top adjusters. I found another bit of slack - so for future reference, don't assume that where the pads were sitting ambiently were all the way back. Apply pressure and then adjust to find bottom.

I reassembled with the drum. Rotation was good with no dragging. Applied the brakes, and its back to a slight drag - nowhere near as bad as before but still dragging. So I compresed with the strap again and when I tightened I heard a sound come from the master. I assume it was the manual forcing of fluid back into the master.

Thoughts? I "could" drive it like this, but should go the extra mile while I'm here… I'm thinking it either needs a stronger return spring, or some black magic with the cylinder or master. Is it possible that air in the line could cause any of these symptoms?

Post by **wesk** » Fri Jun 02, 2017 12:34 am

Air is compressable and usually can only generate enough volume to cause drag when the brake fluid gets too hot. The majority of cases of wheel cylinders pistons not returning fully is stuck, corroded pistons or the master cylinder is not fully releasing pressure. If you must use a strap to force the shoes to seat fully then I would suspect piston fit as the primary issue. If you can fully seat the shoes with your hands easily then I would suspect a soft return spring or the wrong (too long) return spring.

If the piston/wheel cylinder bore prove to be the issue you may have a defective tapered or stepped bore. Or the bore may just be too small. The best way to be sure is to disassemble the wheel cylinder and mic the bore and the piston.

Hawkshadow · Post by **Hawkshadow** » Sun Jun 04, 2017 8:32 am

I disassembled the cylinder and it became clear immediately that there was a problem.

Half of the inside of the cylinder was glazed with built up crud while the other side was perfect.

So out I went to purchase a cylinder hone and cleaned up the cylinder.

After honing I test fitted the piston and noticed that there is a tiny gap between the piston and cylinder. Is this normal and the cup will seal it? They both mic'd in the ballpark of 1". Which brings me to my next question, is it detrimental to have 1" cylinders on the rear? It appears it's supposed to be 1" in the front and 3/4" rear.

Knowing that there was likely a problem with the boot that allowed moisture in to cause the corrosion that I found I inspected both boots. I found that the corroded side had 2-3 different holes in it, while the "good" side had a casting imperfection that was visible on both sides in the same spot, and would likely lead to a hole there in the future. Another strike against Omix parts…

Here I sit thinking about the solution. I assume that I shouldn't just reassemble and worry about it later… Do I just order a repair kit for the boots, or should I replace the whole cylinder? I have to place a rockauto order soon anyway, are the "CJ-3" cylinders and parts I find there suitable for M38? https://www.rockauto.com/en/catalog/je ... r+kit,1956

Post by **wesk** » Sun Jun 04, 2017 9:27 am

Jordan,

What you found is not at all uncommon on a very tired brake system and unfortunately is often the case with new offshore parts.

Even after honing it looks like the one side of your cylinder is still heavily pitted. The small gap on the piston will usually work and the disc can seal it but the disc/cup cannot seal well against a rough pitted surface.

Looks like new is the best way to go.

The CJ3A uses wheel cyl's:
Front: 1" WO# A-1484, LO# FD7379, Ben# 45908
Rear: 3/4" WO# A-6110, LO# FD7568, Ben# 46491

M38 uses:
Front: 1" WO# 800053, LO# FD13092, Ben# 302093, NSN : 2530-00-554-8776 from Factory
Front: 1" WO# 807356, LO# FD16534, Ben# 303141, NSN 2530-00-876-9629 For field service

Rear: 3/4" WO# 800055, LO# FD13093B, Ben# 302094 From Factory
Rear: 3/4" WO# 807357, LO# FD16535, Bem# 303142 For field service.

I suspect your best chance of finding something not made by Omix is to search with the Ben# (Bendix) or the LO# (Wagner/Lockheed)(Federal Mogul) part numbers.

Also try looking at early CJ3B (Up to sn 57348-48092) and CJ5 (Up to sn 57548-83072 listings. They used the front WO# 807356 and the rear WO# 807357. I'd stay away from MB/GPW/CJ2A/CJ3A listings.